When a magnet is passed through a wire loop, which of the following occurs?

• A. The resistance of the wire loop decreases.
• B. An electric current is induced in the wire loop.
• C. The wire loop becomes permanently magnetized.
• D. No effect occurs unless the wire loop is connected to a battery.

Answer: (B)

Verified step by step guidance

1. Understand the principle of electromagnetic induction, which states that a changing magnetic field through a wire loop induces an electric current in the loop.
2. Recognize that when a magnet is passed through a wire loop, the magnetic flux through the loop changes over time.
3. Apply Faraday's Law of Induction, which can be expressed as \(\mathcal{E} = -\frac{d\Phi_B}{dt}\), where \(\mathcal{E}\) is the induced electromotive force (emf) and \(\Phi_B\) is the magnetic flux.
4. Know that the induced emf causes an electric current to flow in the wire loop if the circuit is closed, even if there is no battery connected.
5. Conclude that the correct effect is the induction of an electric current in the wire loop due to the changing magnetic flux, rather than changes in resistance or permanent magnetization.